[Extensions Toolbar] Add a finch config for the redesign

chrome/browser/extensions/extension_action.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_ACTION_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_ACTION_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/stl_util.h"
 #include "chrome/common/extensions/api/extension_action/action_info.h"
 #include "third_party/skia/include/core/SkColor.h"
+#include "ui/gfx/image/image.h"
 
 class GURL;
 
 namespace content {
 class BrowserContext;
 }
 
 namespace extensions {
 class Extension;
 class IconImage;
@@ skipping 254 matching lines @@
   std::map<int, std::map<int, std::vector<gfx::Image> > > declarative_icon_;
 
   // ExtensionIconSet containing paths to bitmaps from which default icon's
   // image representations will be selected.
   scoped_ptr<ExtensionIconSet> default_icon_;
 
   // The default icon image, if |default_icon_| exists.
   // Lazily initialized via LoadDefaultIconImage().
   scoped_ptr<extensions::IconImage> default_icon_image_;
 
+  // The lazily-initialized image for a placeholder icon, in the event that the
+  // extension doesn't have its own icon. (Mutable to allow lazy init.)

[Finnur, 2015/09/22 14:18:32]

... to allow lazy init in GetDefaultIconImage.

[Devlin, 2015/09/23 00:28:35]

Done.

+  mutable gfx::Image placeholder_icon_image_;
+
   // The id for the ExtensionAction, for example: "RssPageAction". This is
   // needed for compat with an older version of the page actions API.
   std::string id_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionAction);
 };
 
 template<>
 struct ExtensionAction::ValueTraits<int> {
   static int CreateEmpty() {
     return -1;
   }
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ACTION_H_